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virtio-vsock is a host/guest communications device. It allows applications in the guest and host to communicate. This can be used to implement hypervisor services and guest agents (like qemu-guest-agent or SPICE vdagent).

  • POSIX Sockets API so existing networking applications require minimal modification (unlike virtio-serial char devices)
  • Listen sockets can accept connections from multiple clients (unlike virtio-serial char devices)
  • No address configuration required inside the guest
  • No Ethernet or TCP/IP for a reduced attack surface for hypervisor services
  • Can be used with VMs that have no network interfaces

Sockets are created with the AF_VSOCK address family. The SOCK_STREAM socket type is currently implemented for in-order, guaranteed stream semantics.




  • Host kernel requirements: CONFIG_VHOST_VSOCK=m
  • Guest kernel requirements: CONFIG_VIRTIO_VSOCKETS=m

Launch a guest and assign it CID 3:

 (host)# qemu-system-x86_64 -device vhost-vsock-pci,guest-cid=3 ...

Language bindings

Projects using vsock

  • nc-vsock - a netcat-like utility for AF_VSOCK
  • xpra - X11 persistent remote display server and client
  • cloonix_vsock - PTY over AF_VSOCK
  • iperf-vsock - iperf3 with AF_VSOCK support
  • socat - VSOCK-CONNECT and VSOCK-LISTEN addresses supported from socat 1.7.4 [2021-01-04]